In automatic printing/developing apparatus, the adjustment of a lens is carried out by rotating a ring or bolts of the adjustment mechanism after loosening the fixing bolts. First, a description will be made regarding the procedure of lens adjustment in a conventional printing/developing apparatus in which a plurality of fixed focus projection lenses are used for printing.
When exchanging lenses, an operator opens a protective cover and sets a lens suitable for a print size and an enlargement ratio. The operator uses a focus chart attached to a negative mask to project the image of the focus chart onto a printing paper to check whether or not the image is properly focused on the paper.
In order to adjust the focus, the operator loosens bolts of the lens, and adjusts the focus by rotating an adjustment ring while observing the image of the focus chart on the printing paper. Then, the operator lightly fastens the bolts to fix the lens for adjusting the optical axis. In this adjustment of the optical axis, the operator moves the cylindrical lens holder after loosening bolts for optical axis adjustment so that the center of the printing paper coincides with the center of the focus chart.
After fastening the bolts for optical axis adjustment to complete the adjustment of the optical axis, the inclination is also adjusted if it is required. If the inclination is adjusted, the optical axis is adjusted again. The focus is then checked, and fine adjustment is carried out to complete the adjustment of the lens.
When the lens is exchanged with a different one, another adjustment is carried out for the new lens after the exchange of lenses.
Thus, with conventional automatic printing/developing apparatus, in the case where a plurality of fixed-focus lenses are used as projection lenses for printing, the lens is exchanged whenever the enlargement ratio is changed. Therefore, the focus and the optical axis must be adjusted for each of the lenses.
Since the adjustment of the focus and the adjustment of the optical axis are manually performed after loosening the fixing bolts and the adjustment bolts, only skilled operators can carry out delicate or fine adjustments without difficulty. Even in the case where the printing is continuously carried out without changing the focus and the optical axis, they must be readjusted in the same manner as the initial adjustment when deviations occur after a lapse of time.
Also, cases may happen in which the same lens cannot be used for different printings even when the enlargement ratio is not changed, because the optical axis must be moved depending on print sizes. In the case where the lens is frequently exchanged, as described above, the position of the lens must be adjusted frequently.
In the case where a variable-focus lens is used as a projection lens for printing, an image on a printing paper moves when the focal distance is changed. Therefore, the position of the lens must be readjusted whenever the focal distance is changed.
An object of the present invention is to provide an automatic adjusting mechanism for an automatic printing/developing apparatus which is capable of delicately or finely adjusting the position of a lens when the lens is exchanged or the focal distance of the lens is changed.